Friday, November 30, 2012

This past week I had an enjoyable time meeting well-known technology writer Robert Scoble who was visiting our Harman facilities in Northridge, CA along with his geek-in-command Sam Levine. As part of the tour, I showed them our Reference Listening Room and Multichannel Listening Lab where we do product research and double-blind evaluations of loudspeakers. We discussed the science and philosophy behind how we design and measure the sound quality of our products.

After running Robert and Sam through a few trials of listener training using our software "How to Listen", I decided to put them through a couple of double-blind listening test trials to see if they had the right stuff. They compared four different brands of floor-standing loudspeakers located behind an acoustically transparent, visually opaque curtain where each loudspeaker is shuffled into the same position via an automated speaker shuffler. All of our tests are conducted double-blind because we have found that even trained listeners are influenced by nuisance variables such as brand, price, size, etc.

In these tests Robert and Sam heard the same four loudspeakers that have been evaluated previously by hundreds of untrained listeners including young, old, American, Asian, and European listeners, whose preferences and performances were compared to those of our panel of trained listeners. From these tests, we have found evidence that most listeners prefer the most accurate, neutral loudspeaker regardless of age, culture or listening experience.

When the listening trials were done, the curtain went up, and Robert and Sam were surprised to discover their favorite choice was the most accurate loudspeaker which was the least expensive. The science works. One of the speakers Robert didn't like was a model that he actually owned: it had excessive amounts of treble and upper bass, which I'm told is mandated by the manufacturer's marketing department who believe that "boom and tizz" are what their customers want. Luckily, I haven't met many of their customers, yet. Robert, then surprised me by turning on his camera doing an impromptu interview, which hopefully you'll enjoy. If you want to learn more about the engineering process and tools behind designing a speaker, check out the interview with one of our speaker engineering stars, Charles Sprinkle.

In my next blog posting I hope to discuss some of the exciting research we've been doing on the relationship between the perception and measurement of headphone sound quality. The goal is to develop the same science for measuring and predicting the sound quality of headphones that we've found useful for designing good sounding loudspeakers. Stay tuned!

It's hard to generalize because there are well-designed and poorly designed horns and waveguides. What is important is that the directivity of the horn matches the woofers at the point they cross-over so you don't get a sudden hole or bump in the sound power or Directivity index.

Listeners seem to like speakers with wide dispersion because the strong lateral reflections they produce increases sense of spaciousness and image widening. However, this only works if you have rooms with side wall reflections. It's less important for multichannel systems where the surrounds produce the lateral reflections for you (assuming the recording was well made).

If you want to see an example of a truly radical horn/waveguide check out the new JBL M2 Reference Monitor. The measurements and sound quality are better than anything I've seen or heard in a Professional product.http://www.jblpro.com/products/recording&broadcast/M2/Tech.html#Spatial

Speaking of JBL measurements... JBL's line of home loudspeakers with horns and large waveguides (Studio and Studio LS series) looks really interesting. Somebody seems to be paying attention to directivity in home speakers :-)

I can't seem to find any complete and objective measurements of those systems, though. Just the usual subjective reviews which I usually skip entirely.

I have been encouraging our marketing people to publish meaningful measurements but it has been slow coming. If you want comprehensive measurements you'll need to purchase a JBL Pro speaker like a LSR. For example, the M2 has a complete set of anechoic measurements showing excellent response on and off-axishttp://www.jblpro.com/products/recording&broadcast/M2/specs.html#.UdHgnhbnlyE

Hi,ponder over the prospect of future investment. It may be in fact worth saving up for an extra 6 months to get a more expensive model that will last longer. Also do your research on brands, which are the most affordable and provide the best quality and durability. Buying a medium priced system Likethat is more durable is a far better option than a cheap system that breaks down.

Recommended Books

Subscribe To

About Me

Sean Olive is Director of Acoustic Research for Harman International, a major manufacturer of audio products for consumer, professional and automotive spaces. He directs the Corporate R&D group, and oversees the subjective evaluation of new audio products including Harman's OEM automotive audio systems. Prior to 1993, he was a research scientist at the National Research Council of Canada where his research focused on the perception and measurement of loudspeakers, listening rooms, and microphones. Sean received a Bachelors degree in Music from the University of Toronto, and his Masters and Ph.D. degrees in Sound Recording from McGill University in Montreal. His Ph.D. research was on room acoustic adaptation and the acoustical interaction between loudspeakers and rooms. Dr. Olive has written over 30 research papers on the perception and measurement of audio for which he was awarded the Audio Engineering Society (AES) Fellowship Award in 1996, and two Publication Awards (1990 and 1995). Sean is the current President of the Audio Engineering Society. For more info see www.linkedin.com/in/seanolive